This invention relates to a data transmitting device with which data at different positions can be monitored at a plurality of places.
The term "data" as herein used is intended to mean data as to sensor output, for example fire detection output of a fire alarm.
There are many cases in which it is necessary to provide a data transmitting device by which the data which generates or is generated at a place can be monitored at a plurality of different locations.
In this connection, two conventional methods are well known in this art. In the first, transmitters and receivers disposed at different locations are interconnected by signal lines separately according to data. In the second, address codes are employed.
In the first method, the data may be transmitted in an analog mode or in a digital mode. However, this method is still disadvantageous in that it is necessary to use a number of signal lines. The number of signal lines is increased as the number of data types increases, and additionally the number of signal lines is increased as the number of locations where data transmission and reception should be effected is increased. Such a system requires extensive maintenance, needs a great deal of human attention, and is generally costly.
In the second method, a number of data can be transmitted through one set of signal lines. However, the second method is also disadvantageous in that the device is intricate and accordingly high in manufacturing cost. In addition, with the device according to the second method, the period of time required for data transmission is increased with increasing numbers of data, and erroneous operation is liable to occur.